Laundry machine

ABSTRACT

A laundry machine includes a cabinet and a tub is provided in the cabinet for holding washing water. A drum is rotatably provided in the tub, and a motor is provided at a rear of a tub for rotating the drum, where the motor includes a stator provided at a rear wall of the tub and a rotor. A transfer preventive unit provided at least at one of the stator and the tub to change a vibration/noise transfer function between the stator and the tub.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the Patent Korean Application No. 10-2009-0093810, filed on Oct. 1, 2009, which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to laundry machines, and, more particularly, to a laundry machine which may reduce vibration and/or noise.

2. Discussion of the Related Art

The laundry machine, used for treating laundry, performs washing, rinsing, spinning and/or drying, and so on. In the meantime, the laundry machine generates vibration and/or noise due to rotation of a drum provided therein, and particularly, generates much vibration and/or noise while performing spinning.

SUMMARY

Accordingly, the present disclosure is directed to a laundry machine.

An object of the present disclosure is to provide a laundry machine which may reduce vibration and/or noise.

Additional advantages, objects, and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a laundry machine includes a motor with a rotor and a stator, wherein at least a vibration/noise transfer function between the stator and a tub is changed.

It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and should not be construed as limiting the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings:

FIG. 1 illustrates a perspective view of an exterior of a laundry machine;

FIG. 2 illustrates a side sectional view of rear portions of a tub and a drum of the laundry machine in FIG. 1;

FIG. 3 illustrates a graph showing frequency vs. vibration and/or noise of a rotor in a related art laundry machine;

FIG. 4 illustrates a graph showing frequency vs. vibration and/or noise of a stator in a related art laundry machine;

FIG. 5 illustrates a graph showing frequency vs. vibration and/or noise of a related art laundry machine;

FIG. 6 illustrates a graph showing frequency vs. vibration and/or noise of a rotor in a laundry machine in accordance with a preferred embodiment of the present invention;

FIG. 7 illustrates a front view of a stator in accordance with a preferred embodiment of the present invention;

FIG. 8 illustrates a front view of a stator in accordance with another preferred embodiment of the present invention;

FIG. 9 illustrates a front view of a stator in accordance with another preferred embodiment of the present invention;

FIG. 10 illustrates a front view of a stator in accordance with another preferred embodiment of the present invention;

FIG. 11 illustrates a graph showing frequency vs. vibration and/or noise of a stator in a laundry machine in accordance with another preferred embodiment of the present invention;

FIG. 12 illustrates a graph showing frequency vs. vibration and/or noise of a laundry machine in a laundry machine in accordance with another preferred embodiment of the present invention; and

FIG. 13 illustrates a partial side sectional view showing a structure for changing a factor of a vibration transfer function of a stator.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Reference will now be made in detail to the specific embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

FIG. 1 illustrates a perspective view of an exterior of a laundry machine.

Referring to FIG. 1, the laundry machine 100 includes a cabinet 10 which forms an exterior of the laundry machine 100, a tub 20 (see FIG. 2) provided in the cabinet 10 for holding washing water and a drum 30 rotatably provided in the tub 20 for holding washing objects.

The cabinet 10 forms an exterior of the laundry machine 100, and has various elements of the laundry machine 100 mounted therein. The cabinet 10 has an opening 14 at a front side and a door 12 for selectively opening/closing the opening 14. According to this, the user can open the door 12, and introduce washing objects into the drum 30 in the cabinet 10 through the opening 14.

The tub 20 is provided in the cabinet 10 for holding washing water, and the drum 30 is rotatably provided in the tub 20 for holding the washing objects. In this configuration, on an inner surface of the drum 30, there may be a plurality of lifters 32 for lifting and dropping the washing objects when the drum 30 rotates.

In the meantime, the tub 20 is suspended by springs (not shown) on an upper side thereof and dampers (not shown) on a lower side thereof. The tub 20 also has a motor 40 (See FIG. 2) at a rear of the tub 20 for rotating the drum 30.

FIG. 2 illustrates a side sectional view of rear portions of the tub 20 and the drum 30 of the laundry machine in FIG. 1.

Referring to FIG. 2, the motor 40 has a rotor 42 and a stator 44 and is mounted to a rear wall 22 of the tub 20. The rotor 42 is connected to the drum 30 through a rotation shaft 34, and the stator 44 is mounted to the rear wall 22 of the tub with a gap between the stator 44 and the rotor 42. Accordingly, when the rotor 42 rotates owing to interaction between the rotor 42 and the stator 44, the drum 30 rotates owing to the rotation of the rotation shaft 34.

In the meantime, when the drum 30 is rotated by the motor 40, the laundry machine 100 generates vibration and/or noise with the rotation of the drum 30. Particularly, in the case where the drum 30 rotates for extracting water from the washing objects and is running at a comparatively high speed, the vibration and/or noise of the laundry machine 100 is intense.

The vibration and/or noise are transmitted from the rotor 42 to the tub 20 through the stator 44. The generation of the vibration and/or noise at the motor will first be reviewed, and then, the laundry machine in accordance with different embodiments of the present invention for preventing the vibration and/or noise will be described.

FIGS. 3, 4 and 5 illustrate graphs showing frequency vs. vibration of the rotor, the stator and the laundry machine of a related art laundry machine, respectively. For reference, the graphs of frequency vs. noise of the rotor, the stator and the laundry machine of the related art laundry machine are similar to the graphs of frequency vs. vibration of the rotor, the stator and the laundry machine, and thus the graphs of frequency vs. noise are not additionally shown.

Referring to FIG. 3, if the rotor 42 of the motor 40 rotates, the rotor 42 vibrates. Furthermore, following an increase in rotation RPM of the rotor 42, the vibration is distinctive at frequencies corresponding to multiples of the rotation RPM. With reference to FIG. 3, it shows that the vibration of the rotor 42 is distinctive at frequencies corresponding to multiples of the rotation RPM.

Moreover, FIG. 3 shows frequency ranges A and B in which the vibration of the rotor 42 become heavier distinctively at regular intervals. The frequency ranges A and B in which the vibration of the rotor 42 become heavier distinctively are caused by characteristics of the rotor 42.

In detail, the frequency ranges A and B ranges in which the vibration of the rotor 42 become heavier correspond to frequencies corresponding to multiples of a greatest common divisor of numbers of slots and poles of the motor 40. For example, the frequency range A range may correspond to the frequency corresponding to a multiple of unity of a greatest common divisor of numbers of slots and poles of the motor 40, and the frequency range B range may correspond to the frequency corresponding to a multiple of two of the greatest common divisor of numbers of slots and poles of the motor 40. In the end, the vibration of the rotor 42 becomes heavier at frequencies corresponding to a multiple of the rotation RPM, and particularly, becomes heavier distinctively at maximum vibration frequencies corresponding to a multiple of a greatest common divisor of numbers of slots and poles.

In the meantime, FIG. 4 illustrates a graph showing a vibration transfer function of the stator 44. In FIG. 4, an abscissa represents the rotation RPM of the rotor (frequency), and an ordinate represents a vibration transfer rate. That is, with reference to FIG. 4, if a vibration transfer function curve is greater then unity, the stator 44 transmits the vibration from the rotor 42 to the tub 20 after amplifying the vibration generated at the rotor 42. If a vibration transfer function curve is smaller then unity, the stator 44 transmits the vibration from the rotor 42 to the tub 20 after attenuating the vibration generated at the rotor 42.

Referring to FIG. 4, the stator 44 has a transfer rate which becomes greater than unity as the rotation RPM of the rotor 42 increases, and becomes the maximum at a certain frequency. According to tests of the inventor, the frequency at which the transfer rate becomes the maximum corresponds to a natural frequency fn of the stator 44, substantially.

In the end, if the rotation RPM of the rotor 42 coincides with the natural frequency fn of the stator 44 substantially, the transfer rate becomes the maximum to amplify the vibration generated at the rotor 42 to the maximum, which is transmitted to the tub 20 through the stator 44. In the meantime, even though varying with different kinds of laundry machines, the natural frequency of the stator 44 falls on a RPM range in which the drum 30 rotates in a spinning course of the laundry machine. Therefore, if the drum 30 is spun for water extraction, the vibration transfer rate of the stator 44 becomes the maximum if the rotation RPM of the rotor coincides with the natural frequency of the stator 44 substantially, and the maximum vibration is transmitted to the tub 20.

Referring to FIG. 4, if the rotation RPM of the rotor 42 passes the natural frequency fn of the stator 44, the transfer rate is reduced, and if the rotation RPM passes a certain frequency, the transfer rate becomes smaller than unity. A frequency when the transfer rate is at unity is called critical frequency fc, at which the vibration transmitted to the tub 20 through the stator 44 is without amplification or attenuation. If the rotation RPM passes the critical frequency fc, the transfer rate becomes smaller than unity, thereby transmitting the vibration to the tub 20 through the stator 44, after attenuating the vibration generated at the rotor 42.

In the meantime, FIG. 5 illustrates a graph showing frequency vs. vibration of the laundry machine 100 compounded by the graphs of FIGS. 3 and 4.

Referring to FIG. 5, the vibration of the laundry machine 100 increases as the rotation RPM of the rotor 42 increases. As described before, this is because the vibration of the rotor 42 becomes heavier at a multiple of the rotation RPM, and such vibration is transmitted through the stator 44. Particularly, the vibration of the laundry machine 100 becomes distinctively heavier in an α range.

In detail, the α range is a range which includes the maximum vibration frequency at which the vibration of the rotor 42 becomes the heaviest, and corresponds to a range which includes the natural frequency fn at which the vibration transfer rate of the stator 44 is at maximum.

That is, the heaviest vibration B (See FIG. 3) is generated at the rotor 42 in the α range, and the vibration is amplified to the maximum (at the natural frequency fn) at the stator 44 and transmitted to the tub 20. Therefore, the vibration of the laundry machine 100 becomes the heaviest in the α range.

If the rotation RPM of the rotor passes the a range, the vibration is reduced slowly. This is because of the reduction of the transfer rate of the transfer function of the stator 44 until the transfer rate of the transfer function becomes smaller than unity when the rotation RPM of the rotor passes the critical frequency fc of the stator 44.

Accordingly, in order to reduce the vibration of the laundry machine, vibration characteristics of the rotor 42 may be changed, or the transfer function of the stator 44 may be changed, which will be described.

In order to change vibration characteristics of the rotor 42, a voltage (power) to the motor 40 may be reduced. By doing this, amplitude of the vibration generated at the rotor 42 may be reduced.

FIG. 6 illustrates a graph showing changes in vibration if vibration characteristic of the rotor 4 is changed. As shown in FIG. 6, it can be noted that the amplitude of the vibration is reduced in comparison to the graph of FIG. 3. That is, by reducing magnitude of the vibration generated at the rotor 42, the vibration generated at the laundry machine may be reduced.

On the other hand, by changing the vibration transfer function of the stator 44, the transmission of the vibration from the stator 44 to the tub 20 may be reduced or prevented. Changing the factors of the transfer function, for example, the natural frequency and/or the critical frequency, will now be described.

An embodiment will be described, in which the factors of the transfer function, for example, the natural frequency and/or the critical frequency, is changed to lower the vibration transfer rate in order to reduce or prevent the transmission of the vibration from the stator 44 to the tub 20.

FIG. 7 illustrates a front view of the stator 44 having a structure for preventing the vibration from transmitting from the stator 44 to the tub 20.

Referring to FIG. 7, the stator 44 has a coil unit 445 for forming electromagnetic force, and an insulator 450 for mounting the coil unit 445 thereto. For convenience's sake, the drawing shows no coil at the coil unit 445, but only teeth 446 on which the coil is wound thereon.

In detail, the stator 44 has a stator core (not shown) having a stack of thin conductive plates, or a long conductive band wound into a helix, and an insulator 450 attached to an upper surface and a lower surface of the stator core to enclose the stator core. The insulator has a plurality of teeth 446 projected from a circumference thereof. As the coil is wound around the tooth, the coil unit 445 is formed. Moreover, the rotor 42 is arranged spaced a distance away from the stator 44, so that the rotor 42 can rotate owing to interaction between the magnets of the rotor 42 and the coil of the stator 44.

In the meantime, if the rotor 42 rotates owing to interaction between the rotor 42 and the stator 44, vibration takes place at the stator 44. If the vibration of the stator transmits to the tub 20 along fastening portion of the stator 44 and the tub 20, the vibration of the tub 20 increases. Accordingly, in the embodiment, transfer preventive unit is provided for preventing transfer of the vibration from the stator 44 to the tub 20.

According to one embodiment, the transfer preventive unit includes a plurality of tub fastening portions 193 and a plurality of deformation portions 191 each arranged between tub fastening portions 193 for connecting the tub fastening portions 193 and deformable for attenuating the vibration.

The transfer preventive unit also includes a connection portion 192 extended from the tub fastening portion 193 in opposite directions and connected to an adjacent deformation portion 191. The connection portion 192 is also bent and extended from the tub fastening portion 193, and bent from the deformation portion 191.

The plurality of deformation portions 191 and the plurality of tub fastening portions 193 are spaced at regular intervals. The tub fastening portions 193, the connection portions 192 and deformation portions 191 can be arranged on the same plane. Therefore, the vibration generated at the stator 44 is attenuated by the connection portion 192. Since the vibration is attenuated and thus, is not easy to transmit to the tub 20, the noise caused by the vibration of the tub 20 may be reduced.

Other embodiments are possible. For instance, in another embodiment, the connection portions 192 may be connected to the deformation portions 191 or the tub fastening portions 193 respectively at an angle. Moreover, the angle can be a right angle, substantially. The angle is not limited to the right angle, but includes all of the angles that can attenuate the vibration from the stator.

The transfer preventive unit may be formed on a plane different from a plane of the insulator 450. That is, the transfer preventive unit may be formed, lower than the insulator 450, or higher than the insulator 450. According to this, since the transfer preventive unit is arranged on a plane different from the insulator 450, the vibration may be effectively attenuated. Moreover, the tub fastening portion 193 of the transfer preventive unit may be arranged on a plane different from the plane of the insulator 450. If the tub fastening portion 193 is arranged on a plane different from the plane of the insulator 450, the bends of the connection portions 192 and the deformation portions 191 may be formed to be extended to planes different from each other.

Effects of the transfer preventive unit will now be described.

When the laundry machine 100 operates, the motor 40 is driven. While the motor 40 is driven, a current is applied to the coil portion 445 of the stator 44. The stator 44 generates an electromagnetic force owing to the current applied and thus, the electromagnetic force generated at the stator 44 interacts with a magnet portion of the rotor 42 to rotate the rotor, which in turn, rotates the rotation shaft 34 of the drum 30. The rotation of the rotation shaft 34 rotates the drum 30.

In the meantime, when the motor is driven, vibration takes place due to a repulsive force of the stator 44. The vibration is transmitted to the stator 44, making the stator 44 vibrate. The embodiment provides a transfer preventive unit for preventing the vibration from transmitting to the tub 20. If the vibration takes place at the stator 44, deformation takes place at the deformation portion 191 of the transfer preventive unit, to absorb the vibration. Accordingly, since the vibration does not transmit from the stator 44 to the tub fastening portion 193, the vibration is not transferred from the stator 44 to the tub 20.

FIG. 8 illustrates an embodiment different from FIG. 7. The embodiment will be described focused on differences from FIG. 7.

Referring to FIG. 8, the transfer preventive unit includes a plurality of tub fastening portions 293 each fastened to the tub 20 for securing the stator 44, a plurality of connection portions 292 each arranged between the tub fastening portions 293 for attenuating the vibration as the connection portion 292 is bent, and a plurality of deformation portions 291 extended from the plurality of connection portions 292, respectively.

That is, the connection portion 292 formed bent from the deformation portion 291 extends the deformation portion 291 to the tub fastening portion 293. In the meantime, the connection portions 292 are respectively connected to the deformation portions at an angle. The angle may be a right angle, substantially.

In the meantime, the connection portion 292 may also include at least one introducing portion 294 or a projection (not shown). The at least one introducing portion 294 may be provided to the tub fastening portion 293, or the deformation portion 291. Moreover, the at least one introducing portion 294 may have a bend. Moreover, if there is a plurality of the introducing portions 294, one introducing portion 294 may be formed to have an angle to the other introducing portion (not shown). In this case, the vibration being transferred to the connection portions 292 is attenuated as the vibration passes through the introducing portions 294 step by step. Accordingly, the vibration can be reduced effectively and quickly, permitting the reduction of vibration from being transferred to the tub.

In the meantime, the tub fastening portion 293 is arranged on a same plane as the insulator 450. Accordingly, the introducing portion 294 may be arranged on the same plane with the tub fastening portion 293. The tub fastening portion 293 can be arranged on a plane different from a plane of the insulator 450. For example, at least one introducing portion 294 may be formed in a stair fashion so as to be arranged on lower planes gradually, and the connection portions 292 may be arranged on a plane lower than the tub fastening portions 293. In the embodiment where the connection portion includes at least one introducing portion 294, the at least one introducing portion 294 may be arranged on a plane lower than the tub fastening portions 293. The connection portions 292 may be arranged on a plane lower than the at least one introducing portion 294. Accordingly, the connection portions 292 may be arranged on a same plane as the tub fastening portions 293. The above description is applicable to the embodiment where the at least one introducing portion 294 is formed in the stair fashion so as to be arranged on higher planes, gradually.

FIG. 9 illustrates another embodiment different from FIG. 7. The embodiment will be described focused on differences from FIG. 7.

Referring to FIG. 9, a transfer preventive unit includes a fixed portion 393 fastened to the tub 20 for preventing deformation caused by a load, and a free portion 391 formed as one body with the fixed portion 393 for deforming which is caused by the vibration of the stator to attenuate the vibration from the stator to the tub 20. In this instance, since the free portion 391 is connected to the insulator 450 to form a curve therewith, the free portion 391 may reduce the vibration from the stator.

FIG. 10 illustrates another embodiment for preventing the vibration from transferring from the stator 44 to the tub 20.

Referring to FIG. 10, the embodiment is provided with a transfer preventive member 50 for preventing the transfer of vibration when the stator 44 is fixed to the tub 20.

The transfer preventive member 50 is provided to the tub fastening portion 193 and is connected to a fastening member, such as a bolt, that fastens the tub fastening portion 193 to the tub 20 for preventing the vibration from transferring from the stator 44 to the tub 20.

That is, the transfer preventive member 50 is formed of an elastic material, such as rubber, for preventing the vibration from transferring from the stator 44 to the tub 20 through the bolt.

In the meantime, the vibration prevention units of the embodiments in FIGS. 7 to 10, not only prevent the transfer of vibration simply, but also serve to change a factor of the vibration transfer function of the stator.

FIG. 11 illustrates a graph showing changes of the vibration after the factor of the vibration transfer function of the stator 44, i.e., the natural frequency and/or the critical frequency is changed.

In detail, if characteristics of the vibration transfer function of the stator 44 is changed, the natural frequency fn and the critical frequency fc of the transfer function drops. Owing to this, overlap of a range δ with a range β may be prevented. Here, the vibration transfer rate of the stator 44 is the maximum in the range δ, and the maximum vibration frequency in which the vibration of the rotor 42 becomes the maximum falls in the range β.

Eventually, as shown in FIG. 12, the vibration of the laundry machine 100 can be reduced distinctively. Actually, the graph in FIG. 12 can be compared to the graph in FIG. 5, to find that a range in FIG. 5 in which the vibration of the laundry machine 100 becomes the maximum does not appear in FIG. 12.

In order to obtain the foregoing effects, it is required to change the characteristic of the vibration transfer function of the stator 44. By changing at least one of the natural frequency fn of the stator 44 and the critical frequency fc of the transfer function, the characteristic of the transfer function may be changed.

In detail, in order to reduce the vibration of the laundry machine 100, it is preferable not to make the range β of the rotor 42 to overlap with the range δ of the stator 44. To do this, the critical frequency fc of the transfer function of the stator 44 may be set smaller than the frequency of the range β of the rotor 42. Preferably, the critical frequency fc of the transfer function of the stator 44 may be adjusted to be lower than the maximum vibration frequency of the rotor 42.

In the meantime, for adjusting the critical frequency fc, it is preferable to adjust the natural frequency fn of the stator 44. That is, the transfer functions in FIGS. 4 and 11 are determined according to the characteristic of the stator 44. In addition, correlation between the natural frequency fn and the critical frequency fc is fixed and according to the transfer function. Accordingly, it is preferable that, by adjusting the natural frequency fn of the stator according to the correlation between the natural frequency fn and the critical frequency fc, the critical frequency fc of the stator is adjusted to be lower than the maximum vibration frequency of the rotor.

In parameters which influence the natural frequency fn of the stator 44, there are mass m and elastic modulus k of the stator 44. Generally, the natural frequency fn is proportional to a square root of a value corresponding to the elastic modulus divided by the mass (fn □√(k/m)). Since the mass m of the stator 44 is fixed according to a capacity of the motor and the like, in most of cases, it is difficult for the mass m to be changed. Therefore, for adjusting the natural frequency fn of the stator 44, it is preferable that the elastic modulus of the stator 44 is changed. It is preferable that the elastic modulus of the stator 44 is reduced to reduce the natural frequency fn.

The elastic modulus of the stator 44 may be reduced by different methods. For an example, a material of the stator may be changed, or a structural change, such as an extension or an incised portion, may be introduced to a part of the stator for changing the elastic modulus of the stator 44. The embodiments described with reference to FIGS. 7 to 10 not only prevent the vibration of the stator 44 from transmission, but also change factors of the vibration transfer function of the stator 44 by means of the vibration transfer preventive unit.

In the meantime, FIG. 13 illustrates a structure according to one embodiment for changing the natural frequency and/or the critical frequency of the vibration transfer function of the stator 44, for example, to change the elastic modulus of the stator 44.

As shown, FIG. 13 illustrates a partial side sectional view showing a structure the insulator 450 of the stator 44. In particular, FIG. 13 illustrates the rear wall 22 of the tub 20 together with the insulator 450 of the stator 44.

Referring to FIG. 13, the insulator 450 of the stator 44 may include an upper insulator 452 and a lower insulator 454, and the stator core is provided in a space between the upper insulator 452 and the lower insulator 454.

The insulator 450 of the stator 44 is mounted to the rear wall 22 of the tub 20. Therefore, the stator 44 is mounted to the rear wall 22 of the tub 20, vertically. In the meantime, the rear wall 22 of the tub 20 may not be formed flat, but curved for reinforcement and mounting other elements thereto.

Accordingly, in an embodiment where the stator 44 is mounted centered on a central portion of the rear wall 22 of the tub 20, an underside surface is not in close contact with the rear wall 22 of the tub 20 completely, but forms a gap with the rear wall 22. Therefore, in the embodiment where the stator 44 is mounted to the rear wall of the tub 20 vertically, if the gap is formed between the underside surface of the stator 44 and the tub 20, the rear wall 22 fails to fully support the stator 44, and in a case the vibration takes place at the stator 44 due to driving of the motor 40, the vibration can be amplified. Particularly, in an embodiment where only a central portion of the stator 44 is fixed to the rear wall 22 of the tub 20, and a periphery of the stator 44, i.e., a teeth portion 446 is not fixed, the vibration may be heavy.

Therefore, those embodiments may be provided with a supporting member 460 on an underside of the insulator 450 of the stator 44. The supporting member 460 connects the underside of the insulator 450 to the rear wall 22 of the tub 20, to support the stator 44. The supporting member 460 may be formed as one unit with the insulator 450, or may be formed as an individual member and mounted to the insulator 450.

In the meantime, if the supporting member 460 is provided, a shape change of the insulator of the stator 44 may take place, which may change the elastic modulus of the stator 44. Moreover, by changing a thickness, a length and a number of the supporting member, the natural frequency fn of the stator may be adjusted, such that the critical frequency fc of the stator may be set to be below the maximum vibration frequency of the rotor.

As has been described, the laundry machine according to various embodiments may reduce noise and/or vibration without requiring any additional element.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the inventions. Thus, it is intended that the claims covers those modifications. 

1. A laundry machine comprising: a cabinet; a tub provided in the cabinet for holding washing water; a drum rotatably provided in the tub; a motor provided at a rear of a tub for rotating the drum, wherein the motor comprises a stator provided at a rear wall of the tub and a rotor; and a transfer preventive unit provided at least at one of the stator and the tub to change a vibration/noise transfer function between the stator and the tub.
 2. The laundry machine as claimed in claim 1, wherein the vibration/noise transfer function of the stator is changed by preventing the vibration of the stator from transmitting to the tub or changing factors of the transfer function of the stator.
 3. The laundry machine as claimed in claim 1, wherein the transfer preventive unit includes a plurality of tub fastening portions and a plurality of deformation portions, and wherein each deformation portion is arranged between tub fastening portions for connecting the tub fastening portions and deformable for attenuating the vibration.
 4. The laundry machine as claimed in claim 3, wherein the transfer preventive unit further includes a connection portion extended from the tub fastening portion in opposite directions and connected to an adjacent deformation portion.
 5. The laundry machine as claimed in claim 4, wherein the connection portion and the adjacent deformation portion are arranged in the same plane.
 6. The laundry machine as claimed in claim 4, wherein the connection portion is connected to at least one of the deformation portion and the tub fastening portion at an angle.
 7. The laundry machine as claimed in claim 6, wherein the connection portion comprises at least one introducing portion connecting to at least one of the deformation portion and the tub fastening portion at an angle.
 8. The laundry machine as claimed in claim 6, wherein the connection portion comprises a plurality of introducing portions, wherein one introducing portion is formed to have an angle with another introducing portion.
 9. The laundry machine as claimed in claim 4, wherein the stator further includes an insulator, and the transfer prevention unit is arranged in a plane different from a plane of the insulator.
 10. The laundry machine as claimed in claim 9, wherein the connection portion comprises a plurality of introducing portions, wherein the plurality of introducing portions form a stair-like structure such that the connection portion is arranged in a plane lower than the tub fastening portion.
 11. The laundry machine as claimed in claim 9, wherein a tub fastening portion of the transfer prevention unit is arranged on a plane different from the plane of the insulator, and a connection portion and a deformation portion of the transfer prevention unit extends at planes different from each other.
 12. The laundry machine as claimed in claim 2, wherein at least one of a natural frequency and a critical frequency of the stator is changed, and the critical frequency is defined as a frequency at which vibration of the rotor is transferred to a tub through the stator without being amplified and attenuated.
 13. The laundry machine as claimed in claim 12, wherein the critical frequency is adjusted to be smaller than a maximum frequency range of the rotor.
 14. The laundry machine as claimed in claim 12, wherein the critical frequency is adjusted to be lower than a maximum vibration frequency of the rotor.
 15. The laundry machine as claimed in claim 14, wherein the critical frequency is adjusted by reducing the natural frequency of the stator.
 16. The laundry machine as claimed in claim 15, wherein the natural frequency is reduced by changing an elastic modulus of the stator.
 17. The laundry machine as claimed in claim 16, further comprising a supporting member on an underside of the stator, and the supporting member connects the stator to the tub.
 18. The laundry machine as claimed in claim 17, wherein at least one of a thickness and a length of the supporting member is adjusted such that a critical frequency of the stator is set below a maximum vibration frequency of the rotor.
 19. The laundry machine as claimed in claim 1, wherein the transfer prevention unit is made of an elastic material. 